The Dutch first came to the area now known as Pennsylvania following Henry Hudson’s exploration of the Delaware River, the state’s waterway to the Atlantic, but they did little more than establish trading posts. Swedes arrived in 1638 and, with the Finns, who came about the same time, spilled over into what is now the Philadelphia area. The Dutch gained control of this New Sweden in 1655, but nine years later England conquered New Netherland, and Pennsylvania became a part of the Duke of York’s new territory, which included New York, New Jersey, and Delaware. In 1673 and 1674 the Dutch regained control, but soon the colony was back under English rule.

None of these early settlements had a more lasting impression on Pennsylvania than did William Penn’s colony. Chartered in 1681 by King Charles II to Penn, a Quaker, Pennsylvania received its new governor aboard the Welcome the following year. The new immigrants were primarily English Quakers, although some were of Welsh, Scottish, and Irish ancestry. Pennsylvania became a royal province briefly from 1692 to 1694, when Penn lost his power over the conflict between the proprietary and popular elements, but the colony then resumed under the proprietary government until the American Revolution. Penn and his descendants left a long-standing influence, especially in terms of governing, in dealing with the native population, and in providing a haven of religious tolerance.

Penn’s “Holy Experiment” encouraged throngs of immigrants in the next century. The two largest groups were the Ulster-Scots (also referred to as the Scots-Irish), who first came in 1707 and in greater numbers from 1728 on, and the Germans, who first arrived in 1683. The Germans, mostly from the Rhine, included subgroups that characterize those who have become known, more culturally than ethnically, as the “Pennsylvania Dutch”— Lutherans, Reformed, Mennonites, Amish, Dunkers (Dunkards), Moravians, Roman Catholics, and Schwenkfelders. After an initial settlement in Germantown (now part of Philadelphia), they became a significant portion of the population in Montgomery, Lancaster, Northampton, Lehigh, Berks, Lebanon, and York counties. The Ulster-Scots settled first in Lancaster, Dauphin, and Chester counties, and then moved westward into the Cumberland Valley. Both groups eventually contributed to the settlement of southwestern Pennsylvania. The westward movements were made despite the Allegheny Mountains that diagonally divide the rectangular-shaped state, and early settlements tended to be made in the valleys, such as the Cumberland, Lebanon, and Lehigh. Other immigrants in the 1700s included Welsh (some of whom were Quakers), French (including Huguenots, later Acadians, and at the end of the century refugees from revolution-torn France and Haiti), Irish, Jews, and African Americans. In spite of the strong Quaker influence, slavery did exist in Pennsylvania, but of the 10,000 African Americans there in 1790, over half were free, and slavery was phased out in the early 1800s.

Most of Pennsylvania’s western settlers had migrated from the eastern part of the province. Some came up from Maryland and Virginia, such as Ulster-Scots and Germans, many of whom had ventured south from Pennsylvania earlier. The Holland Land Company’s territory extended into the northwestern part of Pennsylvania, where New Yorkers met Pennsylvanians coming north from Washington, Allegheny, and other southwestern counties.

It has generally been believed that the Penns dealt fairly with the Native Americans, peacefully acquiring additional territory through treaties and purchase; however, some historians question this. As settlers pushed westward, they forced the natives ahead of them, and the resulting hostilities peaked during the French and Indian War. This conflict caused Pennsylvania to create its first militia in order to defend the frontier settlements.

Connecticut claimed northeastern Pennsylvania and began sending settlers there in the 1750s. A bitter conflict ensued until Connecticut relinquished its claim through the Decree of Trenton in 1782. Other boundary disputes took place with New York and, in the southwest, with Virginia. The most famous, however, was the controversy between the Penns and Lord Baltimore. A temporary line was drawn with Maryland in 1739, but the fixed boundary was not settled until Charles Mason and Jeremiah Dixon’s work was ratified in 1769, creating what became the historic slave/free state division between the North and South.

At the time of the Revolutionary War, Pennsylvania was the “keystone” between the northern and southern colonies since many important events took place in Philadelphia that shaped the emerging nation; in fact, the state’s charter referred to the “Commonwealth” of Pennsylvania, to help express democracy. The British invaded Philadelphia and defeated the patriots at Germantown in 1776, but Pennsylvania is probably best remembered for the harsh winter of 1777–78 that Washington’s poorly trained army spent at Valley Forge. During the War of 1812, Pennsylvanians were instrumental in Commodore Perry’s victory on Lake Erie. (The “Erie Triangle,” now Erie County, was purchased from Native Americans in 1792, to provide the state with a port on the lake. Pennsylvania’s third port is Pittsburgh, whose early development was the result of its location on the Ohio River.) The Commonwealth was greatly involved in the Civil War, including the Battle of Gettysburg, a major turning point for the Union army.

In the nineteenth century Pennsylvania experienced the same growth through transportation systems of canals, roads, and railroads, as did the other mid-Atlantic states. Like its neighbors, Pennsylvania also received a large influx of new immigrants, such as Irish and Germans, followed by Italians, Poles, Scandinavians, Russians, Slovaks, and others. Many of these groups, as well as African Americans migrating north, took part in the tremendous industrial growth of the Commonwealth—in the steel production in Bethlehem and Pittsburgh, the coal mining around Scranton, Wilkes-Barre, and in western Pennsylvania, and the oil fields in the northwest.